1. Field of the Invention
The present invention relates to a speaker system, and more specifically, relates to a speaker system having a bass reflex duct to amplify a bass range.
2. Description of the Related Art
In some speaker systems having a speaker mounted in a speaker box, a bass reflex duct is located at a rear of the speaker inside of the speaker box. The bass reflex duct leads to a bass reflex port opened in the speaker box. In this speaker system, the resonance frequency is determined by the interior volume of the speaker box, and by the diameter and the length of the bass reflex duct according to the Helmholtz resonance phenomenon. Therefore, in order to amplify the bass range, the sound of the desired frequency can be amplified by regulating the dimensions and arrangement of the speaker box and the bass reflex duct.
The resonance frequency can thus be determined by making use of the Helmholtz resonance phenomenon. However, to increase the sound pressure in the resonance, it is necessary to increase the diameter of the bass reflex duct and further to increase the length of the bass reflex duct to reduce the air resistance. However, if the diameter of the bass reflex duct is increased and the length of the bass reflex duct is increased, the size of the speaker box itself is increased. There is a method in which a plurality of bass reflex ducts are provided so as to decrease the diameter of the bass reflex duct and the length of the bass reflex duct, but the structure of the speaker box becomes complicated, and the speaker box cannot be reduced in size. When a compact speaker box is used, only a short bass reflex duct is possible. However, in this case, the diameter of the bass reflex port is of course decreased, and an increase in the sound pressure in the resonance cannot be expected.
In order to overcome the problems described above, preferred embodiments of the present invention provide a speaker system that efficiently directs the back pressure of the speaker to the bass reflex duct to greatly increase the sound pressure in the resonance while greatly miniaturizing the dimensions of the speaker box.
According to one preferred embodiment of the present invention, a speaker system includes a speaker box, a speaker mounted on the speaker box, a bass reflex duct located at a rear of the speaker of the speaker box, and an additional duct that is larger than the bass reflex duct and is disposed around the speaker inside the speaker box, wherein the bass reflex duct is arranged inside the additional duct, and the bass reflex duct and the additional duct overlap each other.
In such a speaker system, the additional duct preferably has a substantially cylindrical shape.
Since the bass reflex duct and the additional duct overlap each other, directionality is provided to the air flowing from the rear of the speaker into the speaker box and the back pressure of the speaker is easily and accurately directed to the bass reflex duct. Most of the back pressure of the speaker is directed and transmitted to the bass reflex duct, and the sound pressure at the resonance frequency is thereby greatly increased.
In particular, due to the substantially cylindrical shape of the additional duct, the air resistance is substantially equal in all directions around the speaker when the back pressure of the speaker propagates inside the speaker box, the leakage of the back pressure is minimized, and most of the back pressure is directed to the bass reflex duct.
In accordance with various preferred embodiments of the present invention, the back pressure of the speaker is accurately and efficiently directed to the bass reflex duct, and the bass range is greatly amplified irrespective of the size and the shape of the speaker box.
Further features, elements, characteristics and advantages of the present invention will be apparent from the detailed description of preferred embodiments with reference to the attached drawings.